The heat shock response (HSR) is a primitive cellular defense mechanism that is known to occur in critically ill patients. Induction of the HSR confers protection in animal models of critical illness, and understanding the mechanisms of this protective effect remains our focus of investigation. Achieving this goal is problematic, however, because of the many components that comprise the HSR. Three of the more important components include: 1) the intrinsic effects of the heat shock stimulus, 2) heat shock protein 70 (HSP70), a major protein expressed in cells subjected to heat shock, and 3) heat shock factor-1 (HSF-1), the major transcription factor regulating heat shock protein expression. The preliminary data supporting this competitive renewal application have opened new areas of nvestigation regarding the respective contributions of each of these three components. Specific Aim I will elucidate the mechanisms by which heat shock modulates interleukin-1beta (IL-1beta)-mediated signaling, by focusing on the regulatory protein-protein interactions that occur following IL-1beta stimulation. As an extension of Specific Aim I, and the currently funded work, Specific Aim II will apply the power of microarray technology and bioinformatics to further elucidate the gene expression patterns that occur following stimulation of human peripheral blood mononuclear cells with sequential heat shock and IL-1beta. This Aim will serve to extend our understanding of the interactions between the heat shock response and proinflammatory signaling to the genomic level and holds tremendous potential for the generation of novel hypotheses. Specific Aims III and 1V will expand to the in vivo setting by specifically examining the respective roles of HSP70 and HSF-1 in conferring protection during murine septic shock secondary to cecal ligation and puncture. Specific Aim III will involve in vivo administration of a TAT-HSP70 chimeric protein, which is capable of efficiently delivering high levels of intracellular HSP70. By increasing intracellular levels of HSP70 by this method, independent of a heat shock stimulus, this Aim will allow us to specifically address the protective role of HSP70 in conferring protection during septic shock. In addition, if this Aim comes to fruition it will form the basis for delivering exogenous HSP70 into the intracellular compartment as a therapeutic strategy. Specific Aim IV will make use of HSF-1 null mutant mice to specifically address the role of HSF-1 in conferring protection during septic shock. Collectively, these Aims will serve to further elucidate the mechanisms by which the HSR confers protection during critical illness and thus could form the basis for clinical application of the heat shock response as a therapeutic strategy.